This invention generally relates to conduits susceptible to being pinched or chafed by other structure in an assembly and to assemblies comprising such conduits and means for detecting and locating a pinch or a chafe.
This invention is generally useful with conduits which non-rigidly extend from components of an assembly such as cables, tubing, hoses and the like. Such conduits are employed for containing one or more electrical cables, optical fibers or various types of fluid lines in their cores, for example. They may also be employed as hydraulic and pneumatic hoses and tension cables. This invention is particularly useful in blind installations where electrical cables, for example, are hidden from view and in installations where cables are not readily accessible and, therefore, it is impossible to determine visually whether or not the cable has been pinched or chafed.
A frequent mode of failure of non-fixed conduits occurs during equipment assembly and later in removal and reassembly when, e.g., a conduit may be inadvertently pinched between a housing and a structural member. Such pinching may lead to an immediate failure or a later failure. Also, a relatively insignificant pinching condition may eventually lead to a progressive failure due to chafing caused, e.g., by vibrations which abrade the conduit. Such failures are of particular concern in aircraft and similar applications where human life is involved and it is not practical to repeatedly check locations of potential failures. In addition, it can be very time-consuming to locate an actual fault or other defective condition known to exist.
In addition to normal operational failures, there is also a concern regarding attempted sabotage of communication lines, computer cables and other relatively accessible vital conduits, which attempt may not be detected. Whether or not detected however, the location of one or more pinches in long and/or many conduits must be determined quickly and the location(s) inspected as soon as possible.
It has been heretofore impractical to locate pinching conditions. Devices such as electric switches of the type used in vehicle monitoring applications, as disclosed by U.S. Pat. No. 3,794,790, cannot locate faults. Apparatus such as is disclosed in copending U.S. application Ser. No. 351498 filed 5/15/89, entitled "Apparatus for Detecting Excessive Chafing of a Cable Arrangement Against an Electrically Grounded Structure", which is assigned to the assignee of the present invention, are not useful unless there has been abrasive chafing.